This invention relates to circuit breakers used to protect an electrical circuit from damage caused by ground fault or a short circuit. If a power surge occurs in a circuit protected by the circuit breaker, for example, the breaker will trip. This will cause a breaker that was in the “on” position to flip to the “off” position, and will interrupt the electrical power leading from that breaker. By tripping in this way, a circuit breaker can prevent damage from occurring on an overloaded circuit, and can also prevent the destruction of the device that is drawing the electricity or other devices connected to the protected circuit.
A typical circuit breaker includes a line and a load. Generally, the line is connected to an incoming electrical power source, e.g., power supplied from a power network such as a utility line. This is sometimes referred to as the input into the circuit breaker. The load, sometimes referred to as the output, connects the circuit breaker to the electrical circuit and components connected to the circuit being fed from the circuit breaker. A circuit breaker may protect an individual component connected directly to the circuit breaker, for example, an air conditioner, or a circuit breaker may protect multiple components, for example, household appliances connected to a circuit which terminates at electrical outlets.
It is known to provide to provide circuit breakers of a fixed type in the panel board. For example, single pole, two-pole and three-pole circuit breakers are all known, which can variously be connected to single phase, two-phase and three-phase circuit for feeding particular circuits. However, a three-phase circuit breaker can only ever be configured as a three-phase circuit breaker and cannot be used to feed a single phase load.
In some applications, it is desirable to have two or more circuit breakers interconnected such that they trip simultaneously. For example, U.S. Pat. No. 4,504,807, which is hereby incorporated by reference, discloses a multi-pole circuit breaker arrangement where a common trip coupler connects the circuit breakers through abutting side walls of the switch cases. In this arrangement, opposing portions cooperate with portions of a U-shaped common trip members inside the adjacent switch cases in order to cause pivotal movement of one of these members to achieve coaxial movement of the coupler and hence of the adjacent trip member in the adjacent case. The multi-pole circuit breaker also has a single handle attached to an elongated internal connector for actuating the breakers in unison with one another.
However, the circuit breaker arrangement disclosed in U.S. Pat. No. 4,504,807 has many disadvantages. For instance, the arrangement of the breakers is bulky and requires a large space to fit in a circuit breaker panel. This is a problem in situations where space is limited and a multi-pole breaker with a slim foot print is needed. Such scenarios regularly happen in modern space efficient circuit breaker panels and in other areas, such as server rooms where it is necessary to have a multi-pole circuit breaker in a slim area between servers.
Another problem with prior art designs, is that in order to assemble the three pole design disclosed, at least three different types of circuit breakers must be manufactured. This is necessitated by the need to interconnect the breakers through a cavity in the abutting side walls of the switch cases. Thus, for the design shown, the middle breaker must have a cavity on both abutting sidewalls, while two side breakers require a cavity on opposing side walls. Still another problem with the prior art design is that not only must differing switch cases be made for the side wall cavities, but also for the single handle arrangement. Thus, while the center breaker has a top opening for the single handle, the switch cases for the side breakers have a flat top. As a result, at least six different cases must be manufactured in order to assemble the breaker disclosed.